Taehui Nam, S. Son, Eojn Kim et al.

Environmental Engineering Research • 2018

Microbial fuel cell (MFC) is an innovative environmental and energy system that converts organic wastewater into electrical energy. For practical implementation of MFC as a wastewater treatment process, a number of limitations need to be overcome. Improving cathodic performance is one of major challenges, and introduction of a current collector can be an easy and practical solution. In this study, three types of current collectors made of stainless steel (SS) were tested in a single-chamber cubic MFC. The three current collectors had different contact areas to the cathode (P 1.0 cm; PC 4.3 cm; PM 6.5 cm) and increasing the contacting area enhanced the power and current generations and coulombic and energy recoveries by mainly decreasing cathodic charge transfer impedance. Application of the SS mesh to the cathode (PM) improved maximum power density, optimum current density and maximum current density by 8.8%, 3.6% and 6.7%, respectively, comparing with P of no SS mesh. The SS mesh decreased cathodic polarization resistance by up to 16%, and cathodic charge transfer impedance by up to 39%, possibly because the SS mesh enhanced electron transport and oxygen reduction reaction. However, application of the SS mesh had little effect on ohmic impedance.

Shimaa E Abd El-Hamid, Islam A Aly, Asmaa R. Heiba et al.

ECS Meeting Abstracts • 2024

Steels are the most used alloys worldwide as they have superior mechanical properties, such as ductility and elasticity. Stainless steel (SS) is used far and wide from infrastructure, households, vehicles, surgical equipment, and medical implants, to electrochemical applications such as supercapacitors, fuel cells, lithium-ion batteries, aqueous rechargeable batteries, and bioelectrochemical systems (BES)1 such as microbial fuel cells (MFCs)2 and microbial electrolysis cells (MECs)3. Even though oxidized stainless steel is a very effective electrode material for BES, it has a high risk of corrosion due to the removal of the protective Cr-based passive oxide layer4. Hereby, this research aims to investigate the corrosion behavior of anodized stainless steel (SS) 304 and 316 mesh in saline water for potential use in BES with high salinity and try to mitigate that corrosion behavior using biocompatible materials. The tested electrodes include SS304 and SS316 mesh before and after anodization (anodized SS, AN-SS), in comparison to AN-SS coated with double layers of graphene oxide (GOx) and poly(3,4-ethylenedioxythiophene) (PEDOT). SS 304 and 316 were anodized using selective leaching protocol to enhance the removal of the bioincompatible and insulating Cr-based layer. The removal of that layer makes SS more susceptible to dissolution and hence further protection is needed. Both GOx and PEDOT were selected to enhance the surface conductivity, biocompatibility, and corrosion resistance. GOx was synthesized using the electro-exfoliation of a graphite sheet at a constant voltage of 10.0 V in terephthalic acid + NaOH solution, followed by centrifuging at 3000 rpm to remove the large particles.5 After several cycles of washing, the freeze-dried GOx was mixed with Nafion for ink preparation, which was used to coat the An-SS using the spray coating method. The coated electrode was further covered with a PEDOT layer, using the chronpotentiometry electropolymerization method (2 mA/cm2, for 10, 30, or 60 min). Several characterization techniques such as SEM, EDX, XPS, FT-IT, Raman spectroscopy, XRD, and TEM, were used to characterize the physical and chemical structure of the coating materials and the the fabricated electrodes. The corrosion behavior was evaluated using potentiodynamic and potentiostatic methods. Based on the anodic polarization results, the corrosion, passivation, and breakdown (due to dissolution) regions were identified. In this presentation, the corrosion behavior (Ecorr, Icorr, breakdown potential, etc) of the studied electrodes will be correlated with their chemical and physical structures. References K.-B. Pu, J.-R. Bai, Q.-Y. Chen, and Y.-H. Wang, in Novel Catalyst Materials for Bioelectrochemical Systems: Fundamentals and Applications, ACS Symposium Series., vol. 1342, p. 165–184, American Chemical Society (2020) https://doi.org/10.1021/bk-2020-1342.ch008. A. A. Abbas, H. H. Farrag, E. El-Sawy, and N. K. Allam, Journal of Cleaner Production, 285, 124816 (2021). Y. Zhang, M. D. Merrill, and B. E. Logan, International Journal of Hydrogen Energy, 35, 12020–12028 (2010). P. Ledezma, B. C. Donose, S. Freguia, and J. Keller, Electrochimica Acta, 158, 356–360 (2015). H. S. Wang et al., Green Chem., 20, 1306–1315 (2018).

Istia Prianti Hidayati, Putty Ekadewi, R. Arbianti et al.

IOP Conference Series: Earth and Environmental Science • 2021

Microbial Electrolysis Cell (MEC) can be used to produce hydrogen gas from organic matter contained in wastewater. However, at the cathode of MECs, hydrogen production may be limited by methanogenesis wherein CO2 and hydrogen protons react to form methane and water. In this study, activated carbon (AC)-Fe was used as a catalyst coated onto SS mesh 304 cathode. AC-Fe/SS was chosen for its high surface area, good activity, and stability. The combination of AC-Fe on SS was expected to increase hydrogen production in MECs. Adsorption and phase inversion were chosen to coat AC-Fe mixture on SS. The research was carried out in a 100 mL MEC reactor with an operating time of 258 h. The produced hydrogen was analyzed for its purity by GC-TCD. Voltage measurements were carried out using a digital multimeter. Additionally, bacterial growth was analyzed by spectrophotometer. The highest fraction of hydrogen gas production was 60% without catalyst (uncoated) over only 0.08% with AC-Fe/SS. The highest value of optical density for bacterial growth was 0.611 for AC-Fe/SS, higher than 0.427 without catalyst. The highest current density was 99.11 mA/m2 for AC-Fe/SS and 59.52 mA/m2 without catalyst. The results suggested AC-Fe/SS coating allows for increased bacterial growth and voltage generation at the cost of an adverse effect on hydrogen gas production.

Jiawei Xie, Xinyi Zou, Yaofeng Chang et al.

SSRN Electronic Journal • 2022

Microbial electrolysis cell (MEC) has been existing problems such as poor applicability to real wastewater and lack of cost-effective electrode materials in the practical application of refractory wastewater. A hydrolysis-acidification combined MEC system (HAR-MECs) with four inexpensive stainless-steel and conventional carbon cloth cathodes for the treatment of real textile-dyeing wastewater, which was fully evaluated the technical feasibility in terms of parameter optimization, spectral analysis, succession and cooperative/competition effect of microbial. Results showed that the optimum performance was achieved with a 12 h hydraulic retention time (HRT) and an applied voltage of 0.7 V in the HAR-MEC system with a 100 μm aperture stainless-steel mesh cathode (SSM-100 μm), and the associated optimum BOD5/COD improvement efficiency (74.75 ± 4.32 %) and current density (5.94 ± 0.03 A·m-2) were increased by 30.36 % and 22.36 % compared to a conventional carbon cloth cathode. The optimal system had effective removal of refractory organics and produced small molecules by electrical stimulation. The HAR segment could greatly alleviate the imbalance between electron donors and electron acceptors in the real refractory wastewater and reduce the treatment difficulty of the MEC segment, while the MEC system improved wastewater biodegradability, amplified the positive and specific interactions between degraders, fermenters and electroactive bacteria due to the substrate complexity. The SSM-100 μm-based system constructed by phylogenetic molecular ecological network (pMEN) exhibited moderate complexity and significantly strong positive correlation between electroactive bacteria and fermenters. It is highly feasible to use HAR-MEC with inexpensive stainless-steel cathode for textile-dyeing wastewater treatment.

Xiaoli Ma, Zhifeng Li, Aijuan Zhou et al.

Figshare • 2017

In comparison to the transportation and storage of hydrogen, methane take advantages in the practical application, while the emerging termed as ‘biohythane’ could be alternative to pure hydrogen or methane in new form of energy recovery from microbial electrolysis cell (MEC). However, the cathodic catalyst even for biohythane still bothers the performance and cost of total MEC, herein, we fabricated the MEC reactor with surrounding stainless steel mesh (SSM) to investigate the feasibility of stainless steel mesh as an alternative to precious metal in biohythane production. The columbic efficiency (CE) of anode was around at 80%, representing the SSM would not limit the activity of anodic biofilm, the SEM image and ATP results accordingly indicated the anodic biofilm was mature and well-constructed. The main contribution of methanogens that quantified by qPCR belonged to the hydrogenotrophic group ( Methanobacteriales ) at cathode. The energy efficiency reached more than 100%, reached up to approximately 150%, potentially suggesting the energetic feasibility of the application to obtain biohythane with SSM in scale-up MEC. Benefiting from the likely tubular configuration, the ohmic resistance of cathode was very low, while the main limitation associated with charge transfer was mainly caused by biofilm formation. The total performances of SSM used in the tubular configuration for biohythane production provide an insight into the implementation of non-precious metal in future scale-up pilot with energy recovery.

Suman Bajracharya, Adolf Krige, Leonidas Matsakas et al.

Fermentation • 2023

Acetate can be produced from carbon dioxide (CO2) and electricity using bacteria at the cathode of microbial electrosynthesis (MES). This process relies on electrolytically-produced hydrogen (H2). However, the low solubility of H2 can limit the process. Using metal cathodes to generate H2 at a high rate can improve MES. Immobilizing bacteria on the metal cathode can further proliferate the H2 availability to the bacteria. In this study, we investigated the performances of 3D bioprinting of Sporomusa ovata on three metal meshes—copper (Cu), stainless steel (SS), and titanium (Ti), when used individually as a cathode in MES. Bacterial cells were immobilized on the metal using a 3D bioprinter with alginate hydrogel ink. The bioprinted Ti mesh exhibited higher acetate production (53 ± 19 g/m2/d) at −0.8 V vs. Ag/AgCl as compared to other metal cathodes. More than 9 g/L of acetate was achieved with bioprinted Ti, and the least amount was obtained with bioprinted Cu. Although all three metals are known for catalyzing H2 evolution, the lower biocompatibility and chemical stability of Cu hampered its performance. Stable and biocompatible Ti supported the bioprinted S. ovata effectively. Bioprinting of synthetic biofilm on H2-evolving metal cathodes can provide high-performing and robust biocathodes for further application of MES.

Xiaoli Ma, Zhifeng Li, Aijuan Zhou et al.

Royal Society Open Science • 2017

In comparison to the transportation and storage of hydrogen, methane has advantages in the practical application, while the emerging product termed as ‘biohythane’ could be an alternative to pure hydrogen or methane in a new form of energy recovery from microbial electrolysis cell (MEC). However, the cathodic catalyst even for biohythane still bothers the performance and cost of total MEC. Herein, we fabricated the MEC reactor with surrounding stainless steel mesh (SSM) to investigate the feasibility of stainless steel mesh as an alternative to precious metal in biohythane production. The columbic efficiency (CE) of anode was around at 80%, representing the SSM would not limit the activity of anodic biofilm; the SEM image and ATP results accordingly indicated the anodic biofilm was mature and well constructed. The main contribution of methanogens that quantified by qPCR belonged to the hydrogenotrophic group ( Methanobacteriales ) at cathode. The energy efficiency reached more than 100%, reached up to approximately 150%, potentially suggesting the energetic feasibility of the application to obtain biohythane with SSM in scale-up MEC. Benefiting from the likely tubular configuration, the ohmic resistance of cathode was very low, while the main limitation associated with charge transfer was mainly caused by biofilm formation. The total performances of SSM used in the tubular configuration for biohythane production provide an insight into the implementation of non-precious metal in future scale-up pilot with energy recovery.

Maliheh Hosseinian, Ghasem Najafpour Darzi, Ahmad Rahimpour

Electroanalysis • 2019

Abstract Nickel oxide nanoparticle (NiO−NP) and polypyrrole (PPy) composite were deposited on a Pt electrode for fabrication of a urea biosensor. To develop the sensor, a thin film of PPy−NiO composite was deposited on a Pt substrate that serves as a matrix for the immobilization of enzyme. Urease was immobilized on the surface of Pt/PPy−NiO by a physical adsorption. The response of the fabricated electrode (Pt/PPy−NiO/Urs) towards urea was analyzed by chronoamperometry and cyclic voltammetry (CV) techniques. Electrochemical response of the bio‐electrode was significantly enhanced. This is due to electron transfer between Ni 2+ and Ni 3+ as the electro‐catalytic group and the reaction between polypyrrole and the urease‐liberated ammonium. The fabricated electrode showed reliable and demonstrated perfectly linear response (0.7–26.7 mM of urea concentration, R 2 = 0.993), with high sensitivity (0.153 mA mM −1 cm −2 ), low detection of limit (1.6 μM), long stability (10 weeks), and low response time (∼5 s). The developed biosensor was highly selective and obtained data were repeatable and reproduced using PPy‐NiO composite loaded with immobilized urease as urea biosensors.

Xinglan Cui, Qingdong Miao, Xinyue Shi et al.

Sustainability • 2023

Microbial fuel cells (MFC) have considerable potential in the field of energy production and pollutant treatment. However, a low power generation performance remains a significant bottleneck for MFCs. Biochar and anatase are anticipated to emerge as novel cathode catalytic materials due to their distinctive physicochemical properties and functional group architectures. In this study, biochar was utilized as a support for an anatase cathode to investigate the enhancement of the MFC power generation performance and its environmental impact. The results of the SEM and XPS experiments showed that the biochar-supported anatase composites were successfully prepared. Using the new cathode catalyst, the maximum current density and power density of the MFC reached 164 mA/m2 and 10.34 W/m2, respectively, which increased by 133% and 265% compared to a graphite cathode (70.51 mA/m2 and 2.83 W/m2). The degradation efficiency of Cr (VI) was 3.1 times higher in the biochar-supported anatase MFC than in the graphite cathode. The concentration and pH gradient experiments revealed that the degradation efficiency of Cr (VI) was 97.05% at an initial concentration of 10 mg/L, whereas a pH value of two resulted in a degradation efficiency of 94.275%. The biochar-supported anatase composites avoided anatase agglomeration and provided more active sites, thus accelerating the cathode electron transfer. In this study, natural anatase and biochar were ingeniously combined to fabricate a green and efficient electrode catalyst, offering a novel approach for the preparation of high-performance positive catalysts as well as a sustainable, economical, and environmentally friendly method for Cr (VI) removal in aqueous solutions.

Glenn Quek, R. J. Vázquez, Samantha R McCuskey et al.

Advanced Materials • 2022

Microbial electrosynthesis—using renewable electricity to stimulate microbial metabolism—holds the promise of sustainable chemical production. A key limitation hindering performance is slow electron‐transfer rates at biotic–abiotic interfaces. Here a new n‐type conjugated polyelectrolyte is rationally designed and synthesized and its use is demonstrated as a soft conductive material to encapsulate electroactive bacteria Shewanella oneidensis MR‐1. The self‐assembled 3D living biocomposite amplifies current uptake from the electrode ≈674‐fold over controls with the same initial number of cells, thereby enabling continuous synthesis of succinate from fumarate. Such functionality is a result of the increased number of bacterial cells having intimate electronic communication with the electrode and a higher current uptake per cell. This is underpinned by the molecular design of the polymer to have an n‐dopable conjugated backbone for facile reduction by the electrode and zwitterionic side chains for compatibility with aqueous media. Moreover, direct arylation polycondensation is employed instead of the traditional Stille polymerization to avoid non‐biocompatible tin by‐products. By demonstrating synergy between living cells with n‐type organic semiconductor materials, these results provide new strategies for improving the performance of bioelectrosynthesis technologies.

E. Nwanebu, Boris Tartakovsky, Fabrice Tanguay-Rioux et al.

ECS Meeting Abstracts • 2024

The goal of this study was to evaluate the impact of NiFe-based metal alloys on the CO2 conversion to carboxylic acids and methane (CH4) in CO2-fed Microbial Electrosynthesis (MES) cells. First, the impact of transition metal alloys on CO2 conversion and product specificity was studied in a MES cell with a conductive polymer cathode with electrodeposited NiFeBi alloy. It was found that the presence of the NiFeBi alloy significantly decreased production of CH4 from 0.5 to 0.1 L (Lc d) – 1, suggesting that methanogenic activity was suppressed in the presence of NiFeBi. On the other hand, the production of carboxylic acids consisting mainly of acetate, propionate and butyrate increased. Specifically, acetate production, which represented 80% of the total carboxylic acids in the cathode liquid increased by 70% to 1.0 g(Lc d)-1. This initial study demonstrated that product selectivity can be influenced by electrodeposition of transition metal alloys such as NiFeBi. It might be preferable to achieve selective production of high value long chain carboxylic acids such as valerate and caproate instead of acetate. Accordingly, in the following experiments NiFeMn and NiFeSn alloys were electrodeposited on carbon felt cathodes and evaluated for enhanced CO2 conversion in MES cells. Both alloys enhanced CH4 production, which reached 0.8 L (Lc d)-1. However, there was no observable improvement in acetate production (0.2 – 0.5 g (Lc d)-1) or other higher chain carboxylic acids in comparison to NiFeBi – coated MES. It was suggested that by using a more biocompatible carbon-based support for alloy electrodeposition, it is possible to improve acetate, butyrate and caproate production. In addition, it is important to facilitate nutrient transport through the three-dimensional (3D) cathode. Limited transport of CO2, H2 and nutrients was identified as a potential rate-limiting factor when using carbon felt electrode. 3D-printed conductive polymer lattices were manufactured and electrodeposited with NiFeSn and NiFeMn alloys. The NiFeMn-coated lattice showed insignificant improvement in higher chain carbon production, however caproate concentration was increased five folds on NiFeSn-coated cathode. Also, electrochemical characterization demonstrated increased hydrogen evolution reaction rate over time. Nevertheless, the throughput of this product remained low at 0.1 g (Lc d)-1). These results indicate that the presence of the NiFe-based metal alloys significantly influenced the electron transfer efficiency from the cathodes to microbial electroactive biofilms leading to increased formation of carboxylic acids in the cathode liquid. Therefore, the next step is to design more efficient 3D conductive polymer lattice electrodeposited with NiFeSn metal alloy to increase CO2 conversion to longer chain carboxylic acids.

D. X. Cao, Hengjing Yan, V. Brus et al.

ACS Applied Materials & Interfaces • 2020

In this work, we aim to provide a better understanding for the reasons behind electron transfer inefficiencies between electrogenic bacterium and the electrode in microbial fuel cells. We do so by using a self-doped conjugated polyelectrolyte (CPE) as the electrode surface, onto which Geobacter sulfurreducens is placed, then using conductive atomic force microscopy (C-AFM) to directly visualize and quantify the electrons that are transferring from the bacterium to the electrode, thereby helping us gain a better understanding for the overpotential losses in MFCs. In doing so, we obtain images that show G. sulfurreducens can directly transfer electrons to an electrode surface without the use of pili, and that overpotential losses are likely due to cell death and poor distribution or performance of the bacteria's haem groups. This unique combination of CPEs with C-AFM can also be used for other studies where electron transfer loss mechanisms need to be understood on the nanoscale, allowing for direct visualization of potential issues in these systems.

Pengbo Zhang, Xin Zhou, Ruilian Qi et al.

Advanced Electronic Materials • 2019

Low organism loading capacity and inefficient extracellular electron transport (EET) are still the bottlenecks hindering the development of bioelectrochemical systems (BESs). It is shown that cationic polythiophene derivative (PMNT) has the ability to simultaneously enhance bacteria biofilm formation, improve the bacteria viability, decrease the resistance value, and accelerate the EET process between exoelectrogen and the electrode. Shewanella oneidensis can form a robust and thick biofilm on the electrode surface in the presence of PMNT. Mediated by electron‐transporting PMNT, even bacteria far away from the electrode can transfer electrons to it. This bioelectrode is utilized as the anode to construct a microbial fuel cell, which exhibits a greatly increased maximum current density and power density and a prolonged lifetime by taking advantage of the unique properties of PMNT. Thus, cationic conductive polymers exhibit great potential as effective biofilm enhancers and electron transporters in BESs.

Alec Agee, Ariel L. Furst

ECS Meeting Abstracts • 2023

Microbial electrocatalysis is an emerging technology which enables electricity generation directly from organic feedstocks, many of which are otherwise difficult to harness for renewable energy. While microbes possess unique advantages for these applications, their use in practical settings is currently limited by inefficient electron transfer from cells to electrodes. To address this bottleneck, we have developed improved electrode materials that combine principles of conductive polymer design with lessons from enzymatic electron transfer reactions. Our polymer electrodes exhibit superior nanoscale electroactive area and enable concerted two-electron transfer from the electron carrier flavin mononucleotide (FMN) to an abiotic surface, a high efficiency mechanism which was previously restricted to biological contexts. Electroactive microbes exhibited greatly improved current production on polymer electrodes in quantitative agreement with in vitro electrochemical properties. Our findings establish bio-inspired functionalization as a useful paradigm to bridge the gap between microbial metabolism and abiotic electrochemistry.

Matteo Grattieri, Nelson D Shivel, Iram Sifat et al.

ChemSusChem • 2017

Microbial fuel cells are an emerging technology for wastewater treatment, but to be commercially viable and sustainable, the electrode materials must be inexpensive, recyclable, and reliable. In this study, recyclable polymeric supports were explored for the development of anode electrodes to be applied in single-chamber microbial fuel cells operated in field under hypersaline conditions. The support was covered with a carbon nanotube (CNT) based conductive paint, and biofilms were able to colonize the electrodes. The single-chamber microbial fuel cells with Pt-free cathodes delivered a reproducible power output after 15 days of operation to achieve 12±1 mW m-2 at a current density of 69±7 mA m-2 . The decrease of the performance in long-term experiments was mostly related to inorganic precipitates on the cathode electrode and did not affect the performance of the anode, as shown by experiments in which the cathode was replaced and the fuel cell performance was regenerated. The results of these studies show the feasibility of polymeric supports coated with CNT-based paint for microbial fuel cell applications.

Nabin Aryal, Pier-Luc Tremblay, Mengying Xu et al.

Frontiers in Energy Research • 2018

Microbial electrosynthesis (MES) is a bioelectrochemical technology developed for the conversion of carbon dioxide and electric energy into multicarbon chemicals of interest. As with other biotechnologies, achieving high production rate is a prerequisite for scaling up. In this study, we report the development of a novel cathode for MES, which was fabricated by coating carbon cloth with conductive poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) polymer. Sporomusa ovata-driven MES reactors equipped with PEDOT:PSS-carbon cloth cathodes produced 252.5 ± 23.6 mmol d-1 acetate per m2 of electrode over a period of 14 days, which was 9.3 fold higher than the production rate observed with uncoated carbon cloth cathodes. Concomitantly, current density was increased to -3.2 ± 0.8 A m-2, which was 10.7-fold higher than the untreated cathode. The coulombic efficiency with the PEDOT: PSS-carbon cloth cathodes was 78.6 ± 5.6%. Confocal laser scanning microscopy and scanning electron microscopy showed denser bacterial population on the PEDOT:PSS-carbon cloth cathodes. This suggested that PEDOT:PSS is more suitable for colonization by S. ovata during the bioelectrochemical process. The results demonstrated that PEDOT: PSS is a promising cathode material for MES.

G. Puthilibai, J. R, S. T

2020 International Conference on Power, Energy, Control and Transmission Systems (ICPECTS) • 2020

Nowadays there are more efforts taken to improve the techniques associated Microbial Fuel cells and to enhance their potential towards practical application. By incorporating the recent developments in biotechnology and organic chemistry, we can increase the efficiency and performance of MFCs. Due to these incorporations we can achieve low production cost, high portability and easy usage. Bio electrodes and polymeric foam substrate are used in MFCs to enhance the efficiency of MFCs to obtain more energy. The usage of Nanotechnology in the application of conducting material on the electrodes of MFCs has improved its performance. The maximum power density obtained is about 4.20W/m^2.

Chia-Ping Tseng, Fangxin Liu, Xu Zhang et al.

Advanced Materials • 2022

Microbial bioelectronic devices integrate naturally occurring or synthetically engineered electroactive microbes with microelectronics. These devices have a broad range of potential applications, but engineering the biotic–abiotic interface for biocompatibility, adhesion, electron transfer, and maximum surface area remains a challenge. Prior approaches to interface modification lack simple processability, the ability to pattern the materials, and/or a significant enhancement in currents. Here, a novel conductive polymer coating that significantly enhances current densities relative to unmodified electrodes in microbial bioelectronics is reported. The coating is based on a blend of poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate) (PEDOT:PSS) crosslinked with poly(2‐hydroxyethylacrylate) (PHEA) along with a thin polydopamine (PDA) layer for adhesion to an underlying indium tin oxide (ITO) electrode. When used as an interface layer with the current‐producing bacterium Shewanella oneidensis MR‐1, this material produces a 178‐fold increase in the current density compared to unmodified electrodes, a current gain that is higher than previously reported thin‐film 2D coatings and 3D conductive polymer coatings. The chemistry, morphology, and electronic properties of the coatings are characterized and the implementation of these coated electrodes for use in microbial fuel cells, multiplexed bioelectronic devices, and organic electrochemical transistor based microbial sensors are demonstrated. It is envisioned that this simple coating will advance the development of microbial bioelectronic devices.

Sergei E. Tarasov, Yulia V. Plekhanova, Aleksandr G. Bykov et al.

Sensors • 2024

A novel conductive composite based on PEDOT:PSS, BSA, and Nafion for effective immobilization of acetic acid bacteria on graphite electrodes as part of biosensors and microbial fuel cells has been proposed. It is shown that individual components in the composite do not have a significant negative effect on the catalytic activity of microorganisms during prolonged contact. The values of heterogeneous electron transport constants in the presence of two types of water-soluble mediators were calculated. The use of the composite as part of a microbial biosensor resulted in an electrode operating for more than 140 days. Additional modification of carbon electrodes with nanomaterial allowed to increase the sensitivity to glucose from 1.48 to 2.81 μA × mM−1 × cm−2 without affecting the affinity of bacterial enzyme complexes to the substrate. Cells in the presented composite, as part of a microbial fuel cell based on electrodes from thermally expanded graphite, retained the ability to generate electricity for more than 120 days using glucose solution as well as vegetable extract solutions as carbon sources. The obtained data expand the understanding of the composition of possible matrices for the immobilization of Gluconobacter bacteria and may be useful in the development of biosensors and biofuel cells.

Md Tabish Noori, Mansi, Shashank Sundriyal et al.

Scientific Reports • 2023

Abstract Microbial electrosynthesis (MES) presents a versatile approach for efficiently converting carbon dioxide (CO 2 ) into valuable products. However, poor electron uptake by the microorganisms from the cathode severely limits the performance of MES. In this study, a graphitic carbon nitride ( g- C 3 N 4 )-metal–organic framework (MOF) i.e. HKUST-1 composite was newly designed and synthesized as the cathode catalyst for MES operations. The physiochemical analysis such as X-ray diffraction, scanning electron microscopy (SEM), and X-ray fluorescence spectroscopy showed the successful synthesis of g- C 3 N 4 -HKUST-1, whereas electrochemical assessments revealed its enhanced kinetics for redox reactions. The g- C 3 N 4 -HKUST-1 composite displayed excellent biocompatibility to develop electroactive biohybrid catalyst for CO 2 reduction. The MES with g- C 3 N 4 -HKUST-1 biohybrid demonstrated an excellent current uptake of 1.7 mA/cm 2 , which was noted higher as compared to the MES using g- C 3 N 4 biohybrid (1.1 mA/cm 2 ). Both the MESs could convert CO 2 into acetic and isobutyric acid with a significantly higher yield of 0.46 g/L.d and 0.14 g/L.d respectively in MES with g- C 3 N 4 -HKUST-1 biohybrid and 0.27 g/L.d and 0.06 g/L.d, respectively in MES with g- C 3 N 4 biohybrid. The findings of this study suggest that g- C 3 N 4 -HKUST-1 is a highly efficient catalytic material for biocathodes in MESs to significantly enhance the CO 2 conversion.

Tahmineh Taheri Dezfouli, R. Marandi, M. Kashefiolasl et al.

SHILAP Revista de lepidopterología • 2019

The modern BioElectrochemical technologies can convert the energy stored in the chemical bonds of biodegradable organic materials to renewable electrical energy through the catalytic reactions of microorganisms while treating the waste waters. The present research was conducted to evaluate the efficiency of a single-chamber Bioelectrochemical system with the carbon aerogel catalyst, as a simple and inexpensive method, in removing the corrosive and odorous sulfur compounds from municipal wastewater simultaneously with electricity generation by using indigenous bacterial consortium. The used bacteria were isolated from local lagoon sediments, and the municipal wastewater was used as the substrate. During six months of the Bioelectrochemical cell operation, the sulfate concentration was dropped to a minimum of 63 ± 57.2 mg/l, indicating the ability of the system to remove 71.8 % of the sulfate from the municipal wastewater and the production of bioenergy. With a 304 mV Open Circulate voltage, the maximum removal of Chemical Oxygen Demand was 80 % and the maximum power density was 1.82 mW/m2. Carbon aerogel, as a novel material with suitable absorbance and resistance to oxidation at urban wastewater pH, can be, therefore, coated on electrodes to facilitate the Oxidation Reduction Reactions and electricity transmission. The existence of elemental sulfur in the sediments showed that these systems could be optimized to recover the elemental sulfur from the municipal wastewater.

Konstantin G. Nikolaev, Jiqiang Wu, Xuanye Leng et al.

ECS Meeting Abstracts • 2023

There is a high interest in living organism-compatible materials associated with electrically active interfaces. Bacteria/electrode interfaces implement smart, functional systems with responses, based on which it is possible to elaborate self-regulating energy generation systems. Carbon materials have a number of advantages, such as biocompatibility, low electrical resistance, and the possibility of increasing the electrode surface on an industrial scale. The most promising approach for the industrial production of electrodes is 3D printing. We propose a 3D-printed carbon electrode – a novel lightweight material for electrodes in bioelectrochemical systems for efficient bioelectricity utilization. The pyrolytic process for manufacturing carbon electrodes is promising for upscaling and industrial applications. However, there is a problem of volume loss when 3D-printed polymers are pyrolyzed in an inert environment. We propose a new strategy for the thermal treatment of 3D-printed polymers that allow for reduced volume loss under pyrolytic carbonization. In addition, to achieve a higher electrode surface area, the graphene aerogel could be impregnated into the 3D-printed scaffolds. Chemical modification of graphene surface can enhance biocompatibility. Specifically, the oxidation of graphene leads to forming a hydrophilic and biocompatible material. We tune graphene hydrophilic properties and electrical conductivity via control over the thermal reduction of the oxidized form of graphene–graphene oxide1. Such sponge morphology affords 3D-printed carbon scaffolds an excellent lightweight host scaffold for microorganisms, in which the graphene nanowalls are homogeneously occupied by S. oneidensis MR-1. We demonstrate a novel sustainable method to produce graphene-based lightweight 3D printed electrode materials for green energy production from biomass. The proposed technology creates the opportunity for novel, innovative, disruptive graphene applications that can lead to the establishment of new energy-related industries and facilitate many startups in the ecosystem. Acknowledgments This work was supported by the Ministry of Education (Singapore) through the Research Centre of Excellence program (grant EDUN C-33-18-279-V12, I-FIM). References Xuanye Leng, Ricardo J. Vazquez, Samantha R. McCuskey, Glenn Quek, Yude Su, Konstantin G. Nikolaev, Mariana C.F. Costa, Siyu Chen, Musen Chen, Kou Yang, Jinpei Zhao, Mo Lin, Zhaolong Chen, Guillermo C. Bazan, Kostya S. Novoselov, Daria V. Andreeva, Carbon, 205, 2023, 33-39.

Tahmineh Taheri Dezfouli, M. Kashefiolasl, R. Marandi et al.

SHILAP Revista de lepidopterología • 2020

The modern bio-electrochemical technologies can convert the energy stored in the chemical bonds of biodegradable organic materials into renewable electrical bioenergy through the catalytic reactions of the microorganisms while treating the wastewaters. The present research has been conducted to study the efficiency of the single-chamber bio electrochemical system with carbon aerogel catalyst as a new, simple and inexpensive approach to remove and recover the valuable but polluting nutrients (nitrogen and phosphorus) from municipal wastewaters and also determines the optimal conditions to scale up the system in countries with hot, dry climates. In the present study, the bacterial consortium was isolated from the sediments of local lagoons, and the municipal wastewater was used as the substrate. During the six months of cell operation, the effluent of BES showed a 54.9% decrease in nitrate concentration and a 59.8% decrease in total N and 90% of phosphate removed from wastewater, the total nitrogen and total phosphate concentration in effluent were 28.9 ± 24.3 mg/l. and 13 ± 46.8 mg/l, respectively. The maximum removal of COD was 80%, and the maximum power density was 1.82mW/m2. Carbon aerogel as a novel material with suitable absorbance and resistance to oxidation by urban wastewater pH can be coated on electrodes to facilitate the Oxidation Reduction reactions and electricity transmission

Anatoly Reshetilov, Yulia Plekhanova, Sergei Tarasov et al.

Membranes • 2019

This work investigated changes in the biochemical parameters of multilayer membrane structures, emerging at their modification with multiwalled carbon nanotubes (MWCNTs). The structures were represented by polyelectrolyte microcapsules (PMCs) containing glucose oxidase (GOx). PMCs were made using sodium polystyrene sulfonate (polyanion) and poly(allylamine hydrochloride) (polycation). Three compositions were considered: with MWCNTs incorporated between polyelectrolyte layers; with MWCNTs inserted into the hollow of the microcapsule; and with MWCNTs incorporated simultaneously into the hollow and between polyelectrolyte layers. The impedance spectra showed modifications using MWCNTs to cause a significant decrease in the PMC active resistance from 2560 to 25 kOhm. The cyclic current–voltage curves featured a current rise at modifications of multilayer MWCNT structures. A PMC-based composition was the basis of a receptor element of an amperometric biosensor. The sensitivity of glucose detection by the biosensor was 0.30 and 0.05 μA/mM for PMCs/MWCNTs/GOx and PMCs/GOx compositions, respectively. The biosensor was insensitive to the presence of ethanol or citric acid in the sample. Polyelectrolyte microcapsules based on a multilayer membrane incorporating the enzyme and MWCNTs can be efficient in developing biosensors and microbial fuel cells.

Julian Tix, Jan-Niklas Hengsbach, Joshua Bode et al.

Microorganisms • 2025

The fermentation of Actinobacillus succinogenes in bioelectrochemical systems offers a promising approach to enhance biotechnological succinate production by shifting the redox balance towards succinate and simultaneously enabling CO2 utilization. Key process parameters include the applied electric potential, electrode material, and reactor design. This study investigates the influence of various carbon fabric electrodes and applied potentials on product distribution during fermentation of A. succinogenes. Building on prior findings that potentials between −600 mV and –800 mV increase succinate production, recent data reveal that more negative potentials, beyond the water electrolysis threshold, trigger electrochemical side reactions, altering product yields. Specifically, succinate decreased from 19.76 ± 0.41 g∙L−1 to 14.1 ± 1.6 g∙L−1, while lactate rose from 0.59 ± 0.12 g∙L−1 to 3.12 ± 0.21 g∙L−1. Contrary to common assumptions, the shift is not primarily driven by oxygen formation. Instead, the results indicate that the intracellular redox potential is affected by both the applied potential and hydrogen evolution, which alters metabolic pathways to maintain redox balance. These findings demonstrate that more negative applied potentials in electro-fermentation processes can impair succinate yields, emphasizing the importance of fine-tuning electrochemical conditions in the system for optimized biotechnological succinate production.

Cristina Gutiérrez-Sánchez, Encarnación Lorenzo

Journal of The Electrochemical Society • 2022

Recently, continuous advances in the development of nanoporous surfaces and their modification with biomolecules, such as redox enzymes have made possible important biolectrochemical applications of these surfaces. New nanoporous surfaces have been designed with a very well controlled architecture that improves the properties of their flat counterparts, resulting in surfaces with a large specific surface area, high conductivity and better electrochemical activity, in particular with regard to increase specific surface area, conductivity and electrochemical activity. The challenge is to achieve suitable pore size, spatial arrangement and pore distribution to facilitate substrate transport and enzyme orientation. The objective is to obtain an ideal nanoporous surface that provides a large surface area, rapid mass transport of substrates and efficient immobilization of redox enzymes to obtain direct electron transfer (DET). Although the electron transfer between the redox centers of the enzyme and the electrode is achieved frequently in the presence of redox mediators, which is known as mediated electron transfer (MET). In this review the latest advances in gold and carbon nanoporous surfaces modified with oxidase enzymes in the development of enzymatic fuel cells or enzymatic biosensors are discussed.

Kristen E. Garcia, Sofia Babanova, William Scheffler et al.

Biotechnology and Bioengineering • 2016

ABSTRACT The engineering of robust protein/nanomaterial interfaces is critical in the development of bioelectrocatalytic systems. We have used computational protein design to identify two amino acid mutations in the small laccase protein (SLAC) from Streptomyces coelicolor to introduce new inter‐protein disulfide bonds. The new dimeric interface introduced by these disulfide bonds in combination with the natural trimeric structure drive the self‐assembly of SLAC into functional aggregates. The mutations had a minimal effect on kinetic parameters, and the enzymatic assemblies exhibited an increased resistance to irreversible thermal denaturation. The SLAC assemblies were combined with single‐walled carbon nanotubes (SWNTs), and explored for use in oxygen reduction electrodes. The incorporation of SWNTs into the SLAC aggregates enabled operation at an elevated temperature and reduced the reaction overpotential. A current density of 1.1 mA/cm 2 at 0 V versus Ag/AgCl was achieved in an air‐breathing cathode system. Biotechnol. Bioeng. 2016;113: 2321–2327. © 2016 Wiley Periodicals, Inc.

Xuanye Leng, Siyu Chen, Samantha R. McCuskey et al.

Advanced Electronic Materials • 2024

Abstract Bioelectrochemical systems (BES) have garnered significant attention for their applications in renewable energy, microbial fuel cells, biocatalysis, and bioelectronics. In BES, bioelectrodes are used to facilitate extracellular electron transfer among microbial biocatalysts. This study is focused on enhancing the efficiency of these processes through microcompartmentalization, a technique that strategically organizes and segregates microorganisms within the electrode, thereby bolstering BES output efficiency. The study introduces a deoxyribonucleic acid (DNA)‐based reduced graphene oxide (rGO) aerogel engineered as a bioanode to facilitate microorganism compartmentalization while providing an expanded biocompatible surface with continuous conductivity. The DNA‐rGO aerogel is synthesized through the self‐assembly of graphene oxide and DNA, with thermal reduction imparting lightweight structural stability and conductivity to the material. The DNA component serves as a hydrophilic framework, enabling precise regulation of compartment size and biofunctionalization of the rGO surface. To evaluate the performance of this aerogel bioanode, measurements of current generation are conducted using Shewanella oneidensis MR‐1 bacteria as a model biocatalyst. The bioanode exhibits a current density reaching up to 1.5 A·m⁻ 2 , surpassing the capabilities of many existing bioanodes. With its abundant microcompartments, the DNA‐rGO demonstrates high current generation performance, representing a sustainable approach for energy harvesting without reliance on metals, polymers, or heterostructures.

Izabella Kłodowska, Joanna Rodziewicz, Wojciech Janczukowicz et al.

Water • 2018

Bioelectrochemical sequencing batch biofilm reactors (SBBRs) may be used as post-anoxic reactors. The aim of this study was to determine how nitrate removal depends on the type of external carbon source and the electric current density (J). The effect of citric acid and potassium bicarbonate on N removal efficiency and the denitrifying bacteria biofilm community at an electric current density of 105 and 210 mA/m2 was determined. Nitrogen removal efficiency depended on the density of the electric current and the carbon source. The highest efficiency of N removal was in the reactor with 210 mA/m2 and citric acid. Regardless of the J value, the addition of an external carbon source to the reactors resulted in a 4–6 fold increase in the relative number of denitrifying bacteria in the biomass in relation to the reactor operated without an electric current flow and organics in the influent. The highest number of denitrifiers was observed in the reactor with an inorganic carbon source and with a density of 105 mA/m2. The main factor determining the shifts in composition of the denitrifying bacteria was the electric current flow. In the reactors operated with the electric current flow, Thauera aminoaromatica MZ1T occurred in the reactors with potassium bicarbonate while Alicycliphilus denitrificans K601 preferred citric acid.

D. Nosek, A. Cydzik‐Kwiatkowska

Journal of Ecological Engineering • 2022

In recent years, much research has focused on energy recovery from biomass as an alternative to fossil fuel usage. Microbial fuel cells (MFCs), which produce electricity via microbial decomposition of organic matter, are of great interest. The performance of an MFC depends on the electrode material; most often, carbon materials with good electrical conductivity and durability are used. To increase the power output of an MFC, the anode material can be modified to reduce the internal resistance and increase the anode surface area. Therefore, this study determined how modifying a carbon felt anode with reduced graphene oxide (rGO) and a combination of rGO with iron (III) oxide (rGO-Fe) affected electricity generation in an MFC fueled with wastewater. A mixed microbial consor tium was used as the anode biocatalyst . The MFC-rGO-Fe produced significantly higher voltages than other cells (average 109.4 ± 75.1 mV in the cycle). Power density curves indicated that modifying the anode with rGO-Fe increased the power of the MFC to 4.5 mW/m 2 , 9.3- and 3.9-times higher than that of the control MFC and the MFC-rGO, respectively. Anode modification reduced the internal resistance of the cells from 1029 Ω in the control MFC to 370 and 290 Ω in the MFC-rGO and MFC-rGO-Fe, respectively. These results show that a mixture of rGO with iron (III) oxide positively affects electricity production and can be successfully used for anode modification in the MFCs fueled with wastewater.

Lizhen Zeng, Lixia Zhang

RSC Advances • 2025

A novel multilayer nanoflake structure of manganese oxide/graphene oxide (γ-MnO2/GO) was fabricated via a simple template-free chemical precipitation method, and the modified carbon felt (CF) electrode with γ-MnO2/GO composite was used as an anode material for microbial fuel cells (MFCs). The characterization results revealed that the γ-MnO2/GO composite has a novel multilayer nanoflake structure and offers a large specific surface area for bacterial adhesion. The electrochemical analyses demonstrated that the γ-MnO2/GO composite exhibited excellent electrocatalytic activity and enhanced the electrochemical reaction rate and reduced the electron transfer resistance, consequently facilitating extracellular electron transfer (EET) between the anode and bacteria. The maximum power density of MFC equipped with the γ-MnO2/GO composite-modified carbon felt anode was 1.13 ± 0.09 W m−2, which was 119% higher than that of the pure commercial carbon felt anode under the same conditions. Thus, the results demonstrate that the multilayer γ-MnO2/GO nanoflake composite-modified carbon felt anode is a promising anode material for high-performance MFC applications.

V. Fedina, A.A. Kovaleva, S. Alferov

XI Международная конференция молодых ученых: биоинформатиков, биотехнологов, биофизиков, вирусологов, молекулярных биологов и специалистов фундаментальной медицины — 2024 : сб. тез. • 2024

Biofuel cells are an actively developing technology that involves the use of living systems to generate electricity. In this work, membrane fractions of Gluconobacter oxydans bacteria were applied on electrodes modified with graphene oxide. The modification of graphite felt leads to an increase in its electrochemical properties, due to which the process of electron transfer between the electrode and the biocatalyst is increased.

Xinmin Liu, Zhaoxin Zhou, Ning Liu et al.

Environmental Technology • 2024

ABSTRACT A novel graphene oxide-modified resin (graphene oxide-macroporous adsorption resin) was prepared and used as a multifunctional carrier in an anaerobic fluidized bed microbial fuel cell (AFB-MFC) to treat phenolic wastewater (PW). The macroporous adsorption resin (MAR) was used as the carrier, graphene oxide was used as the modified material, the conductive modified resin was prepared by loading graphene oxide (GO) on the resin through chemical reduction. The modified resin particles were characterized by scanning electron microscopy (SEM), Raman spectroscopy (RS), specific surface area and pore structure analysis. Graphene oxide-macroporous adsorption resin special model was established using the Amorphous Cell module in Materials Studio (MS), and the formation mechanism of graphene oxide-macroporous adsorption resin was studied using mean square displacement (MSD) of the force module. Molecular dynamics simulation was used to study the motion law of molecular and atomic dynamics at the interface of graphene oxide-macroporous adsorption resin composites. The strong covalent bond between GO and MAR ensures the stability of GO/MAR. When the modified resin prepared in 3.0 mg/mL GO mixture was used in the AFB-MFC, the COD removal of wastewater was increased by 9.1% to 72.44%, the voltage was increased by 84.04% to 405.8 mV, and power density was increased by 765.44% to 242.67 mW/m2. GRAPHICAL ABSTRACT

Elitsa Chorbadzhiyska, Ivo Bardarov, Yolina Hubenova et al.

Catalysts • 2020

In this study, graphite–metal oxide (Gr–MO) composites were produced and explored as potential anodic catalysts for microbial fuel cells. Fe2O3, Fe3O4, or Mn3O4 were used as a catalyst precursor. The morphology and structure of the fabricated materials were analyzed by scanning electron microscopy and X-ray diffraction, respectively, and their corrosion resistance was examined by linear voltammetry. The manufactured Gr–MO electrodes were tested at applied constant potential +0.2 V (vs. Ag/AgCl) in the presence of pure culture Pseudomonas putida 1046 used as a model biocatalyst. The obtained data showed that the applied poising resulted in a generation of anodic currents, which gradually increased during the long-term experiments, indicating a formation of electroactive biofilms on the electrode surfaces. All composite electrodes exhibited higher electrocatalytic activity compared to the non-modified graphite. The highest current density (ca. 100 mA.m−2), exceeding over eight-fold that with graphite, was achieved with Gr–Mn3O4. The additional analyses performed by cyclic voltammetry and electrochemical impedance spectroscopy supported the changes in the electrochemical activity and revealed substantial differences in the mechanism of current generation processes with the use of different catalysts.

Danielle T. Bennett, Anne S. Meyer

Applied and Environmental Microbiology • 2025

ABSTRACT Shewanella oneidensis ( S. oneidensis ) has the capacity to reduce electron acceptors within a medium and is thus used frequently in microbial fuel generation, pollutant breakdown, and nanoparticle fabrication. Microbial fuel setups, however, often require costly or labor-intensive components, thus making optimization of their performance onerous. For rapid optimization of setup conditions, a model reduction assay can be employed to allow simultaneous, large-scale experiments at lower cost and effort. Since S. oneidensis uses different extracellular electron transfer pathways depending on the electron acceptor, it is essential to use a reduction assay that mirrors the pathways employed in the microbial fuel system. For microbial fuel setups that use nanoparticles to stimulate electron transfer, reduction of graphene oxide provides a more accurate model than other commonly used assays as it is a bulk material that forms flocculates in solutions with a large ionic component. However, graphene oxide flocculates can interfere with traditional absorbance-based measurement techniques. This study introduces a novel image analysis method for quantifying graphene oxide reduction, showing improved performance and statistical accuracy over traditional methods. A comparative analysis shows that the image analysis method produces smaller errors between replicates and reveals more statistically significant differences between samples than traditional plate reader measurements under conditions causing graphene oxide flocculation. Image analysis can also detect reduction activity at earlier time points due to its use of larger solution volumes, enhancing color detection. These improvements in accuracy make image analysis a promising method for optimizing microbial fuel cells that use nanoparticles or bulk substrates. IMPORTANCE Shewanella oneidensis ( S. oneidensis ) is widely used in reduction processes such as microbial fuel generation due to its capacity to reduce electron acceptors. Often, these setups are labor-intensive to operate and require days to produce results, so use of a model assay would reduce the time and expenses needed for optimization. Our research developed a novel digital analysis method for analysis of graphene oxide flocculates that may be utilized as a model assay for reduction platforms featuring nanoparticles. Use of this model reduction assay will enable rapid optimization and drive improvements in the microbial fuel generation sector.

Wu Hao, Sang-Hun Lee, Shaik Gouse Peera

Nanomaterials • 2023

Current study provides a novel strategy to synthesize the nano-sized MnO nanoparticles from the quick, ascendable, sol-gel synthesis strategy. The MnO nanoparticles are supported on nitrogen-doped carbon derived from the cheap sustainable source. The resulting MnO/N-doped carbon catalysts developed in this study are systematically evaluated via several physicochemical and electrochemical characterizations. The physicochemical characterizations confirms that the crystalline MnO nanoparticles are successfully synthesized and are supported on N-doped carbons, ascertained from the X-ray diffraction and transmission electron microscopic studies. In addition, the developed MnO/N-doped carbon catalyst was also found to have adequate surface area and porosity, similar to the traditional Pt/C catalyst. Detailed investigations on the effect of the nitrogen precursor, heat treatment temperature, and N-doped carbon support on the ORR activity is established in 0.1 M of HClO4. It was found that the MnO/N-doped carbon catalysts showed enhanced ORR activity with a half-wave potential of 0.69 V vs. RHE, with nearly four electron transfers and excellent stability with just a loss of 10 mV after 20,000 potential cycles. When analyzed as an ORR catalyst in dual-chamber microbial fuel cells (DCMFC) with Nafion 117 membrane as the electrolyte, the MnO/N-doped carbon catalyst exhibited a volumetric power density of ~45 mW m2 and a 60% degradation of organic matter in 30 days of continuous operation.

Asim Ali Yaqoob, Albert Serrà, Showkat Ahmad Bhawani et al.

Polymers • 2022

Although regarded as environmentally stable, bioelectrochemical fuel cells or, microbial fuel cells (MFCs) continue to face challenges with sustaining electron transport. In response, we examined the performance of two graphene composite-based anode electrodes—graphene oxide (GO) and GO–polymer–metal oxide (GO–PANI–Ag)—prepared from biomass and used in MFCs. Over 7 days of operation, GO energy efficiency peaked at 1.022 mW/m2 and GO–PANI–Ag at 2.09 mW/m2. We also tested how well the MFCs could remove heavy metal ions from synthetic wastewater, a secondary application of MFCs that offers considerable benefits. Overall, GO–PANI–Ag had a higher removal rate than GO, with 78.10% removal of Pb(II) and 80.25% removal of Cd(II). Material characterizations, electrochemical testing, and microbial testing conducted to validate the anodes performance confirmed that using new materials as electrodes in MFCs can be an attractive approach to improve the electron transportation. When used with a natural organic substrate (e.g., sugar cane juice), they also present fewer challenges. We also optimized different parameters to confirm the efficiency of the MFCs under various operating conditions. Considering those results, we discuss some lingering challenges and potential possibilities for MFCs.

Yuanfeng Liu, Tingli Ren, Zijing Su et al.

Journal of Materials Chemistry A • 2023

Weak biofilm colonization and sluggish extracellular electron transfer (EET) between the biofilm and anode are major obstacles to achieving high power density in microbial fuel cells (MFCs).

Wenxian Guo, Meiqiong Chen, Xiaoqing Liu et al.

Chemistry – A European Journal • 2021

Abstract A simple, cost‐effective strategy was developed to effectively improve the electron transfer efficiency as well as the power output of microbial fuel cells (MFCs) by decorating the commercial carbon paper (CP) anode with an advanced Mo 2 C/reduced graphene oxide (Mo 2 C/RGO) composite. Benefiting from the synergistic effects of the superior electrocatalytic activity of Mo 2 C, the high surface area, and prominent conductivity of RGO, the MFC equipped with this Mo 2 C/RGO composite yielded a remarkable output power density of 1747±37.6 mW m −2 , which was considerably higher than that of CP‐MFC (926.8±6.3 mW m −2 ). Importantly, the composite also facilitated the formation of 3D hybrid biofilm and could effectively improve the bacteria–electrode interaction. These features resulted in an enhanced coulombic efficiency up 13.2 %, nearly one order of magnitude higher than that of the CP (1.2 %).

Yuyang Wang, Huan Yang, Jing Wang et al.

Coatings • 2023

Microbial fuel cells (MFCs) have exhibited potential in energy recovery from waste. In this study, an MFC reactor with a polyaniline–sodium alginate–graphene oxide (PANI–SA–GO)/carbon brush (CB) hydrogel anode achieved maximum power density with 4970 mW/m3 and produced a corresponding current density of 4.66 A/m2, which was 2.72 times larger than the MFC equipped with a carbon felt film (CF) anode (1825 mW/m3). Scanning electron microscopy indicated that the PANI-SA-GO/CB composite anode had a three-dimensional macroporous structure. This structure had a large specific surface area, providing more sites for microbial growth and attachment. When the charging-discharging time was set from 60 min to 90 min, the stored charge of the PANI-SA-GO/CB hydrogel anode (6378.41 C/m2) was 15.08 times higher than that of the CF (423.05 C/m2). Thus, the mismatch between power supply and electricity consumption was addressed. This study provided a simple and environment-friendly modification method and allowed the prepared PANI–SA–GO/CB hydrogel anode to markedly promote the energy storage and output performance of the MFC.